Sofa



FIG. 1 is a right front perspective view of a sofa showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a right elevational view thereof;

FIG. 4 is a front elevational view thereof; and,

FIG. 5 is a right rear perspective view thereof.

The elements shown in broken lines illustrate portions of the sofa that form no part of the claimed design. 

CLAIM The ornamental design for a sofa, as shown and described. 